In an air jet loom, a sequence of air jets propel a weft yarn (sometimes referred to as weft thread) across a weft insertion region to fabricate a weave. The sequence of air jets are typically controlled via a plurality of valves (sometimes referred to herein as air jet valves), which are typically turned on (sometimes referred to as activated) in rapid succession as the weft thread traverses the weft insertion region.
The sequence of air jets are typically precisely timed, to help ensure that the weft yarn is reliably propelled across the weft insertion region, i.e., completely across the weft insertion region. If a valve associated with a particular air jet is turned on too soon the weft yarn will “bounce off” that particular air jet. If the valve is turned on too late, the weft yarn will sink before it can be “captured” and propelled by the air jet.
Many air jet looms use a microcontroller to operate the air jet loom, including the turn on (or activation) of the air jet valves. Because the air jet valves are typically activated in rapid succession, and because the weft may travel at a relatively high speed, typically around 50 meters per second (m/sec), the microcontroller uses a high speed bus with a very fine timescale of communication to control the air jet valves.
The timing that is desired for the air jets typically depends at in part on the characteristics of the weft yarn, which can vary from roll to roll. Thus, a manual adjustment is typically made to the timing each time a new roll of thread is started.